Question 1

Which of the following best describes the main difference between innate and adaptive immunity?

Accepted Answer

Innate immunity targets a limited number of key structures, while adaptive immunity targets a vast array of specific antigens.

Question 2

A patient receives a kidney transplant and experiences organ rejection. Which molecules are primarily responsible for the recognition of the foreign tissue?

Accepted Answer

Major histocompatibility complex (MHC) antigens

Question 3

Which of the following statements about B cell receptors (BCRs) is correct?

Accepted Answer

Each B cell expresses a unique BCR that recognizes only one epitope.

Question 4

Which class of MHC proteins is found on all nucleated cells except red blood cells?

Accepted Answer

MHC class I

Question 5

A viral protein synthesized inside a host cell will most likely be presented to cytotoxic T cells by which of the following?

Accepted Answer

MHC class I molecules

Question 6

Which of the following is NOT a function of antibodies?

Accepted Answer

Directly killing infected host cells

Question 7

During clonal deletion of T cells, what happens to cells that recognize self-antigens?

Accepted Answer

They undergo apoptosis (negative selection).

Question 8

Which cytokine is primarily responsible for stimulating stem cells to divide?

Accepted Answer

Growth factors

Question 9

A patient is exposed to a pathogen for the second time. Which of the following best explains why the immune response is faster and more effective?

Accepted Answer

Memory cells generated during the primary response quickly recognize and respond to the antigen.

Question 10

Which of the following best describes the role of helper T cells (Th cells) in adaptive immunity?

Accepted Answer

They help activate B cells and cytotoxic T cells through cytokine secretion.

Question 11

Which antibody class is most abundant in body secretions such as saliva and tears?

Accepted Answer

IgA

Question 12

Which of the following is a correct sequence of events in the activation of cytotoxic T cells?

Accepted Answer

Antigen presentation → Helper T cell differentiation → Clonal expansion → Self-stimulation

Question 13

Which of the following best explains why passive immunity is effective more quickly than active immunity?

Accepted Answer

Pre-formed antibodies are provided, so the body does not need to mount its own immune response.

Question 14

A patient with a parasitic worm infection is likely to have elevated levels of which antibody class?

Accepted Answer

IgE

Question 15

Which of the following is a function of regulatory T cells (Treg)?

Accepted Answer

Downregulate adaptive immune responses to prevent autoimmunity.

Question 16

Which of the following best describes the process of antigen presentation by MHC class II molecules?

Accepted Answer

Exogenous antigens are taken up by antigen-presenting cells, processed in vesicles, and presented on MHC class II.

Question 17

Which of the following is a real-world example of naturally acquired active immunity?

Accepted Answer

A child recovers from chickenpox after being exposed to the virus at school.

Question 18

Which of the following best explains why the activities of B and T cells are called 'adaptive'?

Accepted Answer

They are induced and tailored to specific pathogens encountered by the host.

Question 19

Which of the following is a correct statement about the diversity of B cell receptors (BCRs)?

Accepted Answer

The enzyme RAG recombines variable region gene segments to generate antibody diversity.

Question 20

A patient is diagnosed with an autoimmune disease. Which of the following best explains a possible cause based on T cell development?

Accepted Answer

Failure of negative selection during clonal deletion, allowing self-reactive T cells to survive.

Adaptive Immunity: Structure, Function, and Mechanisms

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